Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 8,972,849	$ 8,300,770
Less accumulated depreciation, depletion and amortization	3,216,461	3,133,831	$ 2,991,486
Net property, plant and equipment	5,756,388	5,166,939	4,917,142
Electric
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	2,295,646	2,323,403	2,227,145
Natural gas distribution
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	3,015,164	2,868,853	2,688,123
Pipeline
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	1,051,868	821,697	834,215
Construction materials and contracting
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	2,347,696	2,028,476	1,910,562
Construction services
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	225,758	220,796	213,370
Other
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	36,717	37,545	$ 35,213
Regulated Operation | Electric | Electric Generation Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,056,632	1,133,390
Weighted average depreciable life in years	48 years
Regulated Operation | Electric | Electric Distribution
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 474,037	464,442
Weighted average depreciable life in years	47 years
Regulated Operation | Electric | Electric Transmission
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 562,080	524,155
Weighted average depreciable life in years	65 years
Regulated Operation | Electric | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 62,781	61,766
Regulated Operation | Electric | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 140,117	139,650
Weighted average depreciable life in years	14 years
Regulated Operation | Natural gas distribution | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 21,741	16,836
Regulated Operation | Natural gas distribution | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 225,272	213,976
Weighted average depreciable life in years	14 years
Regulated Operation | Natural gas distribution | Gas Distribution [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,427,779	2,302,121
Weighted average depreciable life in years	50 years
Regulated Operation | Natural gas distribution | Gas Transmission [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 107,721	104,695
Weighted average depreciable life in years	60 years
Regulated Operation | Natural gas distribution | Natural gas storage
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,997	33,014
Weighted average depreciable life in years	39 years
Regulated Operation | Natural gas distribution | General
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 197,653	198,211
Weighted average depreciable life in years	14 years
Regulated Operation | Pipeline | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 263,640	46,690
Regulated Operation | Pipeline | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 50,477	49,640
Weighted average depreciable life in years	17 years
Regulated Operation | Pipeline | Gas Transmission [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 673,344	665,567
Weighted average depreciable life in years	46 years
Regulated Operation | Pipeline | Gas Storage [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 57,670	52,632
Weighted average depreciable life in years	53 years
Nonregulated Operation | Pipeline | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 18	4
Nonregulated Operation | Pipeline | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,719	7,164
Weighted average depreciable life in years	10 years
Nonregulated Operation | Construction materials and contracting | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 50,425	23,803
Nonregulated Operation | Construction materials and contracting | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	149,066	132,948
Nonregulated Operation | Construction materials and contracting | Building and Building Improvements [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 149,262	130,417
Weighted average depreciable life in years	21 years
Nonregulated Operation | Construction materials and contracting | Machinery, vehicles and equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,414,260	1,284,604
Weighted average depreciable life in years	12 years
Nonregulated Operation | Construction materials and contracting | Aggregate reserves [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 584,683	456,704
Nonregulated Operation | Construction services | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 13,467	8,824
Weighted average depreciable life in years	2 years
Nonregulated Operation | Construction services | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,513	7,218
Nonregulated Operation | Construction services | Building and Building Improvements [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 39,039	41,674
Weighted average depreciable life in years	24 years
Nonregulated Operation | Construction services | Machinery, vehicles and equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 166,739	163,080
Weighted average depreciable life in years	7 years
Nonregulated Operation | Other | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,069	34,897
Weighted average depreciable life in years	7 years
Nonregulated Operation | Other | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,648	$ 2,648